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/*
 * Copyright 2008 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.gwt.uibinder.elementparsers;

import com.google.gwt.core.ext.UnableToCompleteException;
import com.google.gwt.safehtml.shared.SafeHtml;
import com.google.gwt.uibinder.rebind.FieldWriter;
import com.google.gwt.uibinder.rebind.UiBinderWriter;
import com.google.gwt.uibinder.rebind.XMLAttribute;
import com.google.gwt.uibinder.rebind.XMLElement;
import com.google.gwt.uibinder.rebind.XMLElement.Interpreter;

import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

/**
 * This is the most generally useful interpreter, and the most likely to be used
 * by a custom parser when calling {@link XMLElement#consumeInnerHtml}.
 * 
    *
  • Assigns computed values to element attributes (e.g. * class="{style.pretty}") *
  • Generates fields to hold named dom elements (e.g. <div * gwt:field="importantDiv">) *
  • Turns <ui:msg> and <ui:attr> elements into methods on a * generated Messages interface *
  • Fails if any element encountered is a widget *
*/ public class HtmlInterpreter implements XMLElement.Interpreter { private class AttributeTypist implements ComputedAttributeInterpreter.Delegate { @Override public String getAttributeToken(XMLAttribute attribute) throws UnableToCompleteException { if (URI_ATTRIBUTES.contains(attribute.getLocalName())) { return writer.tokenForSafeUriExpression(attribute.getElement(), attribute.consumeSafeUriOrStringAttribute()); } return writer.tokenForStringExpression(attribute.getElement(), attribute.consumeStringValue()); } } private static final Set URI_ATTRIBUTES; static { /* * Perhaps we "should" check the element names as well, but the spec implies * that an attribute name always has the same meaning wherever it appears. * It's less work this way, and we're more likely to catch new elements. * * http://dev.w3.org/html5/spec/index.html#attributes-1 * http://www.w3.org/TR/REC-html40/index/attributes.html */ String[] urlAttributes = { "action", "background", "classid", "cite", "codebase", "data", "formaction", "href", "icon", "longdesc", "manifest", "profile", "poster", "src", "usemap"}; URI_ATTRIBUTES = Collections.unmodifiableSet(new HashSet(Arrays.asList(urlAttributes))); } /** * A convenience factory method for the most common use of this class, to work * with HTML that will eventually be rendered under a * {@link com.google.gwt.user.client.ui.UIObject} (or really, any object that * responds to getElement()). Uses an instance of * {@link HtmlMessageInterpreter} to process message elements. * * @param uiExpression An expression that can be evaluated at runtime to find * an object whose getElement() method can be called to get an * ancestor of all Elements generated from the interpreted HTML. */ public static HtmlInterpreter newInterpreterForUiObject(UiBinderWriter writer, String uiExpression) { String ancestorExpression = writer.useLazyWidgetBuilders() ? uiExpression : uiExpression + ".getElement()"; return new HtmlInterpreter(writer, ancestorExpression, new HtmlMessageInterpreter(writer, ancestorExpression)); } private final UiBinderWriter writer; private final InterpreterPipe pipe; /** * Rather than using this constructor, you probably want to use the * {@link #newInterpreterForUiObject} factory method. * * @param ancestorExpression An expression that can be evaluated at runtime to * find an Element that will be an ancestor of all Elements generated * from the interpreted HTML. * @param messageInterpreter an interpreter to handle msg and ph elements, * typically an instance of {@link HtmlMessageInterpreter}. This * interpreter gets last crack */ public HtmlInterpreter(UiBinderWriter writer, String ancestorExpression, Interpreter messageInterpreter) { this.writer = writer; this.pipe = new InterpreterPipe(); pipe.add(new FieldInterpreter(writer, ancestorExpression)); /* * UiTextInterpreter and UiSafeHtmlInterpreter must be invoked before * ComputedAttributeInterpreter to function properly */ pipe.add(new UiTextInterpreter(writer)); pipe.add(new UiSafeHtmlInterpreter(writer)); pipe.add(new ComputedAttributeInterpreter(writer, new AttributeTypist())); pipe.add(new AttributeMessageInterpreter(writer)); pipe.add(messageInterpreter); } public String interpretElement(XMLElement elem) throws UnableToCompleteException { if (writer.useLazyWidgetBuilders() && writer.isElementAssignableTo(elem, SafeHtml.class)) { FieldWriter childField = writer.parseElementToField(elem); return writer.tokenForSafeHtmlExpression(elem, childField.getNextReference()); } if (writer.isImportedElement(elem)) { writer.die(elem, "Not allowed in an HTML context"); } if (elem.getNamespaceUri() != null && !writer.isBinderElement(elem)) { // It's not a widget, and it's not a ui: element. writer.die(elem, "Prefix \"%s:\" has unrecognized xmlns \"%s\" (bad import?)", elem.getPrefix(), elem.getNamespaceUri()); } return pipe.interpretElement(elem); } }




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